This invention relates generally to injection molding and more particularly to a torpedo which is mounted at the front end of a nozzle to provide a fixed ring gate.
The use of injection molding torpedoes having an elongated central shaft with a pointed tip to provide a hot tip gate is well known. An early example is shown in the applicants' U.S. Pat. No. 4,450,999 which issued May 29, 1984. This has the disadvantage that the improvement in thermal conductivity in the gate area is limited by the shape of the hot tip.
It is also known to provide a core ring gate around a valve member which extends through the cavity as well as the gate and is reciprocated between the open and closed positions. An example is seen in the applicants' U.S. Pat. No. 4,521,179 which issued Jun. 4, 1985. In addition to requiring actuating mechanism, this configuration has the disadvantage that it is only suitable for molding products with a core hole through them.